LXR uboot/arch/arm/imx-common/timer.c

   1/*
   2 * (C) Copyright 2007
   3 * Sascha Hauer, Pengutronix
   4 *
   5 * (C) Copyright 2009 Freescale Semiconductor, Inc.
   6 *
   7 * See file CREDITS for list of people who contributed to this
   8 * project.
   9 *
  10 * This program is free software; you can redistribute it and/or
  11 * modify it under the terms of the GNU General Public License as
  12 * published by the Free Software Foundation; either version 2 of
  13 * the License, or (at your option) any later version.
  14 *
  15 * This program is distributed in the hope that it will be useful,
  16 * but WITHOUT ANY WARRANTY; without even the implied warranty of
  17 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  18 * GNU General Public License for more details.
  19 *
  20 * You should have received a copy of the GNU General Public License
  21 * along with this program; if not, write to the Free Software
  22 * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
  23 * MA 02111-1307 USA
  24 */
  25
  26#include <common.h>
  27#include <asm/io.h>
  28#include <div64.h>
  29#include <asm/arch/imx-regs.h>
  30#include <asm/arch/clock.h>
  31
  32/* General purpose timers registers */
  33struct mxc_gpt {
  34        unsigned int control;
  35        unsigned int prescaler;
  36        unsigned int status;
  37        unsigned int nouse[6];
  38        unsigned int counter;
  39};
  40
  41static struct mxc_gpt *cur_gpt = (struct mxc_gpt *)GPT1_BASE_ADDR;
  42
  43/* General purpose timers bitfields */
  44#define GPTCR_SWR               (1 << 15)       /* Software reset */
  45#define GPTCR_FRR               (1 << 9)        /* Freerun / restart */
  46#define GPTCR_CLKSOURCE_32      (4 << 6)        /* Clock source */
  47#define GPTCR_TEN               1               /* Timer enable */
  48
  49DECLARE_GLOBAL_DATA_PTR;
  50
  51static inline unsigned long long tick_to_time(unsigned long long tick)
  52{
  53        tick *= CONFIG_SYS_HZ;
  54        do_div(tick, MXC_CLK32);
  55
  56        return tick;
  57}
  58
  59static inline unsigned long long us_to_tick(unsigned long long usec)
  60{
  61        usec = usec * MXC_CLK32 + 999999;
  62        do_div(usec, 1000000);
  63
  64        return usec;
  65}
  66
  67int timer_init(void)
  68{
  69        int i;
  70
  71        /* setup GP Timer 1 */
  72        __raw_writel(GPTCR_SWR, &cur_gpt->control);
  73
  74        /* We have no udelay by now */
  75        for (i = 0; i < 100; i++)
  76                __raw_writel(0, &cur_gpt->control);
  77
  78        __raw_writel(0, &cur_gpt->prescaler); /* 32Khz */
  79
  80        /* Freerun Mode, PERCLK1 input */
  81        i = __raw_readl(&cur_gpt->control);
  82        __raw_writel(i | GPTCR_CLKSOURCE_32 | GPTCR_TEN, &cur_gpt->control);
  83
  84        gd->arch.tbl = __raw_readl(&cur_gpt->counter);
  85        gd->arch.tbu = 0;
  86
  87        return 0;
  88}
  89
  90unsigned long long get_ticks(void)
  91{
  92        ulong now = __raw_readl(&cur_gpt->counter); /* current tick value */
  93
  94        /* increment tbu if tbl has rolled over */
  95        if (now < gd->arch.tbl)
  96                gd->arch.tbu++;
  97        gd->arch.tbl = now;
  98        return (((unsigned long long)gd->arch.tbu) << 32) | gd->arch.tbl;
  99}
 100
 101ulong get_timer_masked(void)
 102{
 103        /*
 104         * get_ticks() returns a long long (64 bit), it wraps in
 105         * 2^64 / MXC_CLK32 = 2^64 / 2^15 = 2^49 ~ 5 * 10^14 (s) ~
 106         * 5 * 10^9 days... and get_ticks() * CONFIG_SYS_HZ wraps in
 107         * 5 * 10^6 days - long enough.
 108         */
 109        return tick_to_time(get_ticks());
 110}
 111
 112ulong get_timer(ulong base)
 113{
 114        return get_timer_masked() - base;
 115}
 116
 117/* delay x useconds AND preserve advance timstamp value */
 118void __udelay(unsigned long usec)
 119{
 120        unsigned long long tmp;
 121        ulong tmo;
 122
 123        tmo = us_to_tick(usec);
 124        tmp = get_ticks() + tmo;        /* get current timestamp */
 125
 126        while (get_ticks() < tmp)       /* loop till event */
 127                 /*NOP*/;
 128}
 129
 130/*
 131 * This function is derived from PowerPC code (timebase clock frequency).
 132 * On ARM it returns the number of timer ticks per second.
 133 */
 134ulong get_tbclk(void)
 135{
 136        return MXC_CLK32;
 137}
 138